Xdmcp not work

[darkshvein]

Client show "Display not authorized to connect"
ubuntu 11.04
kdmrc:
[Xdmcp] Enable=true
Willing=/etc/kde4/kdm/Xwilling
cat /etc/kde4/kdm/Xwilling
#! /bin/sh
# The output of this script is displayed in the chooser window

# (instead of "Willing to manage").

load=`uptime|sed -e 's/^.*load[^0-9]*//'`
nrusers=`who|cut -c 1-8|sort -u|wc -l|sed 's/^[ ]*//'`
s=""; [ "$nrusers" != 1 ] && s=s

echo "${nrusers} user${s}, load: ${load}"

Network wired, Via router. M.b. any port blocked?[br]